Currently, aortic stenosis (AS) is considered a "surgical disease" with no medical therapy available to improve any clinical outcomes, including symptoms, time to surgery, or long-term survival. Thus far, randomized studies involving statins have not been promising with respect to slowing progressive valve stenosis. Beyond the valve, two common consequences of aortic stenosis are hypertrophic remodeling of the left ventricle (LV) and pulmonary venous hypertension; each of these has been associated with worse heart failure symptoms, increased operative mortality, and worse long-term outcomes. Whether altering LV structural abnormalities, improving LV function, and/or reducing pulmonary artery pressures with medical therapy would improve clinical outcomes in patients with AS has not been tested. Animal models of pressure overload have demonstrated that phosphodiesterase type 5 (PDE5) inhibition influences nitric oxide (NO) - cyclic guanosine monophosphate (cGMP) signaling in the LV and favorably impacts LV structure and function, but this has not been tested in humans with AS. Studies in humans with left-sided heart failure and pulmonary venous hypertension have shown that PDE5 inhibition improves functional capacity and quality of life, but patients with AS were not included in those studies. The investigators hypothesize that PDE5 inhibition with tadalafil will have a favorable impact on LV structure and function as well as pulmonary artery pressures. In this pilot study, the investigators anticipate that short-term administration of tadalafil to patients with AS will be safe and well-tolerated.

The following with be reported - frequency of the following: hypotension (SBP < 90 mmHg), symptomatic hypotension (symptoms of presyncope or syncope associated with SBP <90), syncope, hospitalization for a cardiac reason, myocardial infarction, new onset or worsening heart failure, and new sustained arrhythmia requiring intervention

Active drug will be encapsulated to look identical to the placebo pill. Subjects will take a single oral dose of tadalafil once daily from the time of randomization until study completion (6 months). Subjects will begin by taking 20 mg (1 pill) daily for 3 days before having the dose increased to 40 mg (2 pills) once daily. If the increase to 40mg daily is not tolerated, then the dose will be decreased back to 20mg daily.

Other Names:

Cialis

Adcirca

Placebo Comparator: Placebo in Diabetic Cohort

Drug: Placebo

The placebo pill will be encapsulated to look identical to the active drug pill. Subjects will take a single oral dose of placebo once daily from the time of randomization until study completion (6 months). Subjects will begin by taking 1 pill daily for 3 days before having the dose increased to 2 pills once daily. If the increase to 2 pills is not tolerated, then the dose will be decreased back to 1 pill daily.

Active Comparator: Tadalafil in Non-Diabetic Cohort

Drug: Tadalafil

Active drug will be encapsulated to look identical to the placebo pill. Subjects will take a single oral dose of tadalafil once daily from the time of randomization until study completion (6 months). Subjects will begin by taking 20 mg (1 pill) daily for 3 days before having the dose increased to 40 mg (2 pills) once daily. If the increase to 40mg daily is not tolerated, then the dose will be decreased back to 20mg daily.

Other Names:

Cialis

Adcirca

Placebo Comparator: Placebo in Non-Diabetic Cohort

Drug: Placebo

The placebo pill will be encapsulated to look identical to the active drug pill. Subjects will take a single oral dose of placebo once daily from the time of randomization until study completion (6 months). Subjects will begin by taking 1 pill daily for 3 days before having the dose increased to 2 pills once daily. If the increase to 2 pills is not tolerated, then the dose will be decreased back to 1 pill daily.

Detailed Description:

Subjects with moderately severe to severe aortic stenosis (AS), left ventricular hypertrophy (LVH), diastolic dysfunction, preserved ejection fraction, and no planned aortic valve replacement over the next 6 months will be eligible for this randomized, double-blind, placebo-controlled, pilot study. There will be a diabetic cohort (n=32) and non-diabetic cohort (n=24); each cohort will be randomized 1:1 to tadalafil vs. placebo. During a baseline study visit, the following will be obtained: clinical data, 6 minute walk, quality of life questionnaire, blood draw, and an echocardiogram. A 3-day run-in will occur to initially assess tolerability and compliance. If the drug is tolerated during this run-in period, participants will be randomized. An MRI will also be performed during this randomization visit. Follow-up study visits and testing will occur at 6 and 12 weeks and 6 months.

The subject and treating physician are not planning on a valve replacement procedure to occur during the next 6 months

Ambulatory

Normal sinus rhythm

18 years of age and older

Able and willing to comply with all the requirements for the study

Exclusion Criteria:

Need for ongoing nitrate medications

SBP < 110mmHg or MAP < 75mmHg

Moderately severe or severe mitral regurgitation

Moderately severe or severe aortic regurgitation

Contraindication to MRI

Creatinine clearance < 30 mL/min

Cirrhosis

Pulmonary fibrosis

Increased risk of priapism

Retinal or optic nerve problems or unexplained visual disturbance

If a subject requires ongoing use of an alpha antagonist typically used for benign prostatic hyperplasia (BPH) (prazosin, terazosin, doxazosin, or tamsulosin), SBP < 120 mmHg or MAP < 80 mmHg is excluded

Need for ongoing use of a potent CYP3A inhibitor or inducer (ritonavir, ketoconazole, itraconazole, rifampin)

Current or recent (≤ 30 days) acute coronary syndrome

O2 sat < 90% on room air

Females that are pregnant or believe they may be pregnant

Any condition which the PI determines will place the subject at increased risk or is likely to yield unreliable data

Unwilling to provide informed consent

Contacts and Locations

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study.
To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below.
For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01275339